This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Mammary gland biology is currently studied using cell culture, in vivo mouse models, and mammary gland transplantations. While human mammary tissues have been obtained for study via oncological or breast reduction surgery, access to normal tissue during lactation is non-existent. Therefore genome-wide transcriptome studies of the lactation cycle have been limited to rodents and agricultural species. A novel, non-invasive technique for the in vivo study of mammary epithelial cells during lactation has recently been demonstrated in humans. However, milk samples have not been compared to normal mammary biopsies. Our proposed experiments seek to address, by comparison of mammary biopsies and milk in a primate species, whether milk fat globule RNA is representative of mammary epithelial RNA. Establishment of non-invasively acquired rhesus macaque milk fat globule RNA as a substitute for human mammary RNA will provide a foundation for future research in cancer biology and diagnosis, infant-maternal nutrition, infant-maternal immunology, breast infections during lactation, and other diagnostics of maternal health. Successful demonstration of this assay in macaques will also complement ongoing lactation studies at the CNPRC by enabling researchers to assay local regulation of the mammary gland in a non-invasive manner.